1. Field of the Invention
The present invention relates to an improvement in an auto-focus camera which sets three or more areas in a photographing frame, and performs focus adjustment of a photographing lens on the basis of the defocus amount of an object in a selected one of these areas.
2. Related Background Art
In recent years, as an automatic focus detection apparatus for a camera, the following focus detection system is widely used. In this system, a light beam coming from an object and passing through different exit pupil areas (distance measuring areas) of a photographing lens is focused on a pair of line sensors, and a relative positional displacement amount between a pair of image signals obtained by photoelectrically converting object images formed on the line sensors is calculated, thereby detecting the defocus amount of an object. Furthermore, a system in which a plurality of focus selection systems are arranged to allow focus detection in a plurality of areas is also known. Of cameras having a plurality of focus detection systems, as a means for selecting a distance measuring area to be focused from the plurality of focus detection systems, a camera which automatically selects the area in accordance with a predetermined algorithm is known.
In order to control the above-mentioned auto-focus automation techniques to more faithfully reflect a photographer's will, a technique for detecting a position of a gazing point of a photographer in a finder, i.e., in a photographing frame, and selecting a distance measuring area to be focused on the basis of the visual axis (gazing point) detection result is also proposed.
Note that the camera which has a plurality of focus detection systems and automatically selects a distance measuring area to be focused from the plurality of focus detection systems in accordance with a predetermined algorithm is disclosed in Japanese Laid-Open Patent Application Nos. 1-288812, 1-288813, and the like. Also, the technique which has the visual axis detection means and applies it to the automation technique of a camera is disclosed in Japanese Laid-Open Patent Application No. 1-241511, and the like.
In the conventional camera which has a plurality of focus detection systems and automatically selects a distance measuring area to be focused from the plurality of focus detection systems, since the algorithm is designed to automatically select the area from all the distance measuring areas of the camera as selective items, a distance measuring area which is not intended by a photographer at all may be focused in some cases.